Several large financial firms have significant Haskell codebases, plenty of random cryptocurrency startups are Haskell based, some of the Google TPU chips are/were written in Haskell/Clash, Facebook has a big Haskell codebase, Starbucks and Target use it, there are several national security/defense firms extensively using Haskell, etc. etc.

Just because you don't see a bunch of blog posts like "We rewrote our <useless product> in <language du jour>!" doesn't mean it's not being used. In fact, more serious companies tend to lean less heavily on the developer social media publicity circuit.